Early Fertilization For Rice
DR. RON LEVY
BATON ROUGE, LOUISIANA
Rice seed is mostly carbohydrates stored in tissue called endosperm. The embryo makes up most of the rest of the seed. Germination begins with the imbibition of water. The seed swells, gains weight, conversion of carbohydrates to sugars begins and the embryo is activated. Nutrition from the endosperm can supply the growing embryo for about three weeks. Fertilization timing and water management are similar for both drill-seeded and dry broadcast- seeded rice. Phosphorus (P), potassium (K) and micronutrient fertilizers should be applied preplant or pre-flush based on soil texture and soil test results.
The addition of 15 to 20 pounds of preplant or pre-flush nitrogen (N) is generally recommended to ensure against nitrogen deficiency in seedling rice. Early nitrogen deficiency can reduce tillering and yield potential. Application of large amounts of preplant nitrogen should also be avoided in a dry-seeded system since wetting and drying cycles before the permanent flood is established can lead to the loss of much of this nitrogen.
Most of the nitrogen fertilizer should be applied to a dry soil surface within 3 days prior to permanently flooding the field. The remainder of the nitrogen requirement should be applied midseason. In some cases, all of the nitrogen fertilizer can be applied ahead of the permanent flood if the precise nitrogen requirement for a field is known and if the permanent flood can be maintained throughout the season. If a field must be drained, however, for any unforeseen reason such as water weevil larva control or straight head, appreciable amounts of nitrogen can be lost requiring reapplication of nitrogen. When the required nitrogen fertilizer rate is not known or the field will be drained before harvest for any reason,
apply 60 to 70 percent of the estimated nitrogen fertilizer requirement prior to flood establishment. Additional nitrogen fertilizer should be applied at midseason at the beginning of internode elongation (IE) green ring. Native soil fertility, soil type and other factors affect nitrogen fertilizer efficiency. Rice growers should determine the nitrogen rate that provides optimal grain yield on their soil and production system. ∆
DR. RON LEVY: LSU AgCenter